2-chloro-ethyl phosphonic acid esters and plant growth regulating agents containing same as active ingredient

ABSTRACT

The present invention relates to new compounds of the general formula (I) ##STR1## wherein R stands for hydrogen, C 1-8  straight or branched chained alkyl, C 1-4  haloalkyl, C 1-4  alkoxy-C 1-2  alkyl, 
     R 1  stands for 2,3-dihydro-2,2-dimethyl-benzofuran-7-yl, 4-methyl-coumarin-7-yl, 2,2,4-trimethyl-(2H)-chromen-5-yl or 2,2,4-trimethyl-(2H)-chromen-7-yl and Me stands for a monovalent cation and represents the salt of the acid. 
     The new compounds show plant growth regulating activity and can be used as active ingredient of plant growth regulators.

The present invention relates to 2-chloro-ethyl phosphonic acid estersof the general formula (I) ##STR2## the preparation of said compounds aswell as plant growth regulating agents containing as active ingredientthe compounds of general formula (I).

In Hungarian patent specification No. 160,618 esters of 2-chloro-ethylphosphonic acid with pyrocatechol, 4-chloro-pyrocatechol, phenol,salicylic alcohol, salicylic acid, resorcinol and other alcanols aredisclosed. The biological activity of the esters is demonstrated ontomatoe, on bean arts, on ananas and on cereals.

In DD-PS No. 132,632 the alkoxy trichloromethyl esters of 2-halo-ethylphosphonic acid are disclosed having plant growth regulating anddesiccant activity.

In U.S. Pat. No. 4,042,370 the cyanoalkyl, alkoxy-carbonyl-alkyl-alkinyloxo and thio esters of 2-chloro-ethyl phosphonic acid are disclosedwhich are used for the treatment of rubber trees in order to increaselatex crop. In J. Prakt. Chem. 1975 798-806 among others cyclic estersof 2-chloro ethyl phosphonic acid are disclosed and in these esters onthe carbon attached to the oxygen can be hydrogen, alkyl or acycloalkylene group can be attached to the two oxygen atoms.

The new 2-chloro-ethyl phosphonic derivatives can be characterised bythe general formula (I) wherein

R stands for hydrogen, C₁₋₈ straight or branched chained alkyl, C₁₋₄haloalkyl, C₁₋₄ alkoxy-C₁₋₂ alkyl or a monovalent cation,

R¹ stands for 2,3-dihydro-2,2-dimethyl-benzofuran-7-yl,4-methyl-coumarin-7-yl, 2,2,4-trimethyl-(2H)-chromen-5-yl or2,2,4-trimethyl-(2H)-chromen-7-yl, Me stands for a monovalent cation andrepresents the salt of the acid.

The new compounds show a plant growth regulating activity.

The compounds of the 2-chloro-ethyl-phosphonic acid esters can beprepared by reacting the corresponding benzofuran or coumarin orchromene derivative with 2-chloro-ethyl-phosphonic acid dichloride inthe presence of an acid binding agent. When preparing the diesters thecorresponding benzofuran, coumarin or chromene derivative and thealcanol are reacted in the presence of an acid binding agent, and thedesired end-product is isolated by methods known per se.

The salts of the 2-chloro-ethyl phosphonic acid esters can be preparedby reacting the diester without isolation with the corresponding metalhydroxide.

From the active ingredients of the general formula (I) the usualcompositions such as water-soluble concentrates, wetting agents,wettable powders, granules, emulsifyable concentrates, colloidal aqueoussuspensions can be prepared.

The plant growth regulating activity means an activity of the activeingredient on the physiological processes of the plant growth dependingon the time of the use, on the development stage of the plant and on theused concentration.

The compositions can be prepared by methods known per se such asadmixing the active ingredients with carriers i.e. liquid solventsand/or solid carriers and optionally surfactants, such as emulsifying ordispersing agents can be used.

The compositions contain 0.1-95% by mass active ingredient. The activeingredients are usually used in the form of compositions or they can beused in the form of solutions, emulsifyable concentrates, suspensions,wettable powders, dusting agents or granules by spraying orvapourization. The active ingredient concentrations can be varied withina wide range depending on the character of the used active ingredients.

The new active ingredients and the compositions prepared from the activeingredients are illustrated in the following Examples.

EXAMPLE 1 Preparation of 2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-monoester (CompoundNo. 1)

To 70 ml. anhydrous benzene 16.42 g (0.1 mole)2,3-dihydro-2,2-dimethyl-7-hydroxy-benzofuran and as acid binding agent12.11 g. (0.1 mole) N,N-dimethyl-aniline are added whereafter 21.93 g.(0.12 mole) 2-chloro-ethyl-phosphonic acid dichloride are added dropwiseto the reaction mixture at room temperature under stirring. The reactionmixture is then heated for 2 hours and the reaction is monitored by gaschromatographic analysis.

When the reaction is completed the mixture is cooled and at 20°-30° C. asolution of 5.6 g. (0.14 mole) sodium hydroxide in 30 ml. water is addeddropwise and the mixture is heated for 2 hours. The reaction mixture isthen cooled, the benzene layer is separated, dried above anhydroussodium sulphate and benzene is distilled off in vacuo on a rotatory filmevaporator. The residual yellowish, thick, oily substance is washed withhexane and its purity is checked by gas chromatography. n_(D) ²⁵=1.5225.

2-Chloro-ethyl-phosphonic acid-O-(4'-methylcoumarin-7'-yl)-ester issimilarly prepared but 2,3-dihydro-2,2-dimethyl-7-hydroxy-benzofuran wasreplaced by 4-methyl-umbelliferon as starting material. The obtainedproduct is a thick gummy product, n_(D) ²⁴ =1.5650.

EXAMPLE 2 Preparation of 2-chloro-ethyl-phosphonic acidO-methyl-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester (Compound No.2)

16.42 g. (0.1 mole) 2,3-dihydro-2,2-dimethyl-7-hydroxy-benzofuran, 12.11g. (0.1 mole) dimethyl-7-hydroxy-benzofuran, 12.11 g. (0.1 mole)N,N-dimethylaniline and 21.93 g. (0.12 mole) 2-chloro-ethyl-phosphonicacid dichloride are reacted as disclosed in Example 1.

To the cooled reaction mixture 3.52 g. (0.11 mole) methanol and 12.11 g.(0.1 mole) N,N-dimethyl-aniline are added dropwise. The reaction mixtureis then heated for 2 hours. The reaction is then monitored by gaschromatographic analysis. After cooling the reaction mixture theprecipitated N,N-dimethyl-aniline-hydrochloride is filtered and thebenzene solution is washed with diluted hydrochloric acid solution withaqueous sodium hydroxide solution and then with water. It is dried aboveanhydrous sodium sulphate and the solvent is distilled off in vacuo on arotatory film evaporator.

Thus 15.76 g. orange, thick, oily liquid substance are obtained, n_(D)²⁵ =1.5180.

By using the reaction components of the following table compounds 3-10can be prepared by the process disclosed in Examples 1 and 2.

    __________________________________________________________________________    Number                                                                              Reaction component                                                                           Compound of the general                                  of the                                                                              aliphatic                                                                           heterocyclic                                                                           formula (I)                                              compound                                                                            alcohol                                                                             phenol   R          R.sup.1        end product                    __________________________________________________________________________    3     2-chloro- ethanol                                                                   2,3-dihydro- 2,2-dimethyl- 7-hydroxy- benzofuran                                       ClCH.sub.2CH.sub.2                                                                        ##STR3##      2-chloro-ethyl- phosphonic                                                    acid- Omethyl-O(2,3-                                                          dihydro-2,2-di- methyl-benz                                                   ofuran- 7-yl)-ester            4     n-octyl- alcohol                                                                    2,3-dihydro- 2,2-dimethyl- 7-hydroxy- benzofuran                                       C.sub.8 H.sub.17                                                                          ##STR4##      2-chloro-ethyl- phosphonic                                                    acid-O(2- chloro-ethyl)-                                                      O(2,3-dihydro-2,2-                                                            dimethyl-benzofuran-                                                          7-yl)ester                     5     2-butoxy- ethanol                                                                   2,3-dihydro- 2,2-dimethyl- 7-hydroxy- benzofuran                                       C.sub.4 H.sub.9O CH.sub.2CH.sub.2                                                         ##STR5##      2-chloro-ethyl- phosphonic                                                    acid-O(2- butoxy-ethyl)-O(2                                                   ,3- dihydroxy-2,2-                                                            dimethyl-benzofuran-                                                          7-yl)-ester                    6     sec.butanol                                                                         2,3-dihydro- 2,2-dimethyl- 7-hydroxy- benzofuran                                        ##STR6##                                                                                 ##STR7##      2-chloro-ethyl- phosphonic                                                    acid-O(2- methyl-propyl)-                                                     O2,3-dihydro-2,2- dimethyl-                                                   benzofuran- 7-yl)-ester        7       --  4-methyl-um- belliferon                                                                H                                                                                         ##STR8##      2-chloro-ethyl- phosphonic                                                    acid-O(4- methyl-coumarin-                                                    -yl)-ester                     8     methanol                                                                            4-methyl-um- belliferon                                                                CH.sub.3                                                                                  ##STR9##      2-chloro-ethyl- phosphonic                                                    acid-O methyl-O(4-methyl-                                                     coumarin-7-yl)-ester           9     methanol                                                                            2,2,4-trimethyl- (2H)5-hydroxy- chromene                                               CH.sub.3                                                                                  ##STR10##     2-chloro-ethyl- phosphonic                                                    acid- Omethyl-(2,2,4-                                                         trimethyl-(2H) chromene-5-y                                                   l)-ester                       10    methanol                                                                            2,2,4-trimethyl- (2H)7-hydroxy- chromene                                               CH.sub.3                                                                                  ##STR11##     2-chloro-ethyl- phosphonic                                                    acid- Omethyl-O(2,2,4-                                                        trimethyl- (2H)chromene-7-                                                    l)-ester                       __________________________________________________________________________

EXAMPLE 3

Emulsifiable concentrate can be prepared from the following components:

    ______________________________________                                        Compound No. 2        10%     by mass                                         mixture of polyoxyethylene-                                                                         5%      by mass                                         alkyl-aryl-ether and alkyl-                                                   phenol alkoxalate                                                             (Emulsogen I-40, manufactured by                                              Hoechst)                                                                      toluene               85%     by mass                                                               100%    by mass                                         ______________________________________                                    

EXAMPLE 4

Emulsifiable concentrate:

    ______________________________________                                        Compound No. 3        70%     by mass                                         α-[4-(1,1,3,3-tetramethyl-butyl)-                                                             10%     by mass                                         phenyl]-ω-hydroxy-poly(oxy-1,2-                                         ethandiyl) (Triton X-100)                                                     isophoron             20%     by mass                                                               100%    by mass                                         ______________________________________                                    

EXAMPLE 5

Wettable powder

    ______________________________________                                        Compound No. 8        20%     by mass                                         sodium-oleyl-methyl-tauride                                                                         7%      by mass                                         (Arkopon T-Hoechst)                                                           sodium-lignin-sulphonate                                                                            5%      by mass                                         colloidal synthetic silicon dioxyde                                                                 28%     by mass                                         kaolin                40%     by mass                                                               100%    by mass                                         ______________________________________                                    

EXAMPLE 6

Dusting agent

    ______________________________________                                        Compound No. 2     1%      by mass                                            talc               99%     by mass                                                               100%    by mass                                            ______________________________________                                    

EXAMPLE 7

Colloidal aqueous suspension concentrate

    ______________________________________                                        Compound No. 10       30%     by mass                                         mixture of polyoxyethylene-mono-                                                                    6%      by mass                                         laurate and alkylphenol-alkoxalates                                           (Emulsogen IC-HOECHST)                                                        magnesium-lignin-sulphonate                                                                         4%      by mass                                         lecithine             4%      by mass                                         colloidal synthetic silicon dioxide                                                                 26%     by mass                                         water                 30%     by mass                                                               100%    by mass                                         ______________________________________                                    

EXAMPLE 8

Granule

    ______________________________________                                        Compound No. 4     5%      by mass                                            kaolin             95%     by mass                                                               100%    by mass                                            ______________________________________                                    

EXAMPLE 9

Emulsifiable concentrate

    ______________________________________                                        Compound No. 1         85%     by mass                                        polyoxyethylene-sorbitan-monolaurate                                                                 10%     by mass                                        (Tween-20, Atlas)                                                             methylene-chloride     5%      by mass                                                               100%    by mass                                        ______________________________________                                    

EXAMPLE 10

Water soluble concentrate

    ______________________________________                                        Compound No. 12        10%     by mass                                        polyoxyethylene-sorbitan-monolaurate                                                                 8%      by mass                                        (Tween-20, Atlas)                                                             water                  82%     by mass                                                               100%    by mass                                        ______________________________________                                    

EXAMPLE 11

Dusting agent

    ______________________________________                                        Compound No. 15     1%      by mass                                           talc                99%     by mass                                                               100%    by mass                                           ______________________________________                                    

EXAMPLE 12

Wettable powder

    ______________________________________                                        Compound No. 18       70%     by mass                                         fatty alcohol sulphonate                                                                            6%      by mass                                         sodium-lignin-sulphonate                                                                            4%      by mass                                         colloidal synthetic silicon dioxide                                                                 16%     by mass                                         kaolin                4%      by mass                                                               100%    by mass                                         ______________________________________                                    

EXAMPLE 13

Granule

    ______________________________________                                        Compound No. 14     5%      by mass                                           vermiculite         95%     by mass                                                               100%    by mass                                           ______________________________________                                    

Biological tests

2-Chloroethyl-phosphonic acid esters and salts thereof according to theinvention were tested on plant growth regulating activity in green houseby using tomato, soya beans and sunflower as indicating plants. Theplants were seeded into pots filled with turf or the plants were set asseedlings. The post-emergent treatment was carried out on tomato at adevelopment stage of 20-30 cm. and on soybeans and sunflower at adevelopment stage of 10-20 cm. In the course of the tests a controlwithout active ingredient (K) was always used and as active ingredient2-chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester(Compound No. 2) and as referential compounds 2-chloro-ethyl-phophonicacid (F) and 2,2-dimethyl-2,3-dihydro-7-hydroxy-benzofuran (G) wereused. In the tomato indicating plant pre-emergent treatment was alsocarried out. The used doses and the obtained results are summarized inthe tables.

When evaluating the biological tests the change of the height of plantswas determined. The height change in the case of tomato treatedpost-emergence was determined on the 4., 7. and 10. day after thetreatment, in soybeans and sunflower on the 7th day after the treatmentand in case of the treatment pre-emergence, the plant's height was alsodetermined on the 7th day after treatment.

The results are given in the percent of the starting height.

                  TABLE I                                                         ______________________________________                                        Effect of post-emergent treatment on the growth of tomato                              Treatment                                                                             Change in the % of the                                                dose    starting height                                              Composition                                                                              kg./ha.   4. day   7. day 10. day                                  ______________________________________                                        K                    29       53     71                                       Compound 2 0.5       47       81     101                                                 1.0       47       77     100                                                 2.0       41       71     85                                       F          0.5       42       69     86                                                  1.0       41       68     76                                                  2.0       43       65     70                                       G          0.5       31       63     78                                                  1.0       37       62     80                                                  2.0       38       70     83                                       ______________________________________                                    

The table shows that 2-chloro-ethyl-phosphonicacid-O-methyl-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester increasethe height of tomato at a great extent related to the untreated control.The increase of the height was in inverse ratio to the increase of thedose. At a rate of 2 kg./ha. its activity was the same as that of2-kg./ha. 2,2-dimethyl-2,3-dihydro-7-hydroxy-benzofuran and that of 0.5kg./ha. of 2-chloro-ethyl-phosphonic acid.

                  TABLE 2                                                         ______________________________________                                        Effect of post-emergent treatment on the growth of soybeans                                  Change in the % of the starting                                       Treatment                                                                             height                                                                  dose      I.     II.  III. IV.  V.   --                              Composition                                                                            kg./ha.   rep.   rep. rep. rep. rep. X                               ______________________________________                                        K                  23.4   26.9 21.1 25.1 26.2 24.5                            Comp. 2  0.5       17.1   24.5 29.0 25.8 23.1 23.4                                     1.0       14.9   24.5 24.0 23.1 17.1 20.7                                     2.0       16.0   13.3 18.6 18.0 14.5 16.1                            F        0.5       13.0   11.3 14.1 15.1  9.4 12.6                                     1.0       15.1   10.6 12.4 11.4 11.4 12.2                                     2.0        6.6   10.0  8.5  9.5  8.8  8.7                            G        0.5       33.8   28.2 32.6 37.6 33.3 33.1                                     1.0       22.6   30.4 35.8 22.1 33.8 28.9                                     2.0       23.8   18.4 20.5 20.6 19.5 20.6                            ______________________________________                                         rep. = repetition                                                        

The table shows that as opposed to the results on tomato a higher rateof (1.0, 2.0 kg./ha.) 2-chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester had aresult of decreasing the height of soybeans. The extent of this decreasewas lower than the values measured at similar rates of2-chloro-ethyl-phosphonic acid. When using2,2-dimethyl-2,3-dihydro-7-hydroxy-benzofuran alone the doses of 0.5 and1.0 kg./ha intensively increased whereas the dose of 2 kg./ha. slightlydecreased the growth.

                  TABLE 3                                                         ______________________________________                                        Effect of post-emergent treatment on the growth of sunflower                                 Change in the % of the starting                                       Treatment                                                                             height                                                                  dose      I.     II.  III. IV.  V.                                   Composition                                                                            kg./ha.   rep.   rep. rep. rep. rep. .sup.--X                        ______________________________________                                        K                  33.0   38.8 31.1 27.9 26.7 31.5                            Compound 1.0       24.3   22.2 24.2 28.4 29.6 25.7                            2        2.0       21.2   17.0 20.0 20.5 21.5 20.0                            F        1.0       6.3    5.0  6.1  5.4  6.2  5.8                                      2.0       5.8    5.1  5.0  4.0  2.7  4.5                             G        1.0       27.8   25.0 38.9 33.3 26.5 30.3                                     2.0       32.9   35.0 35.3 30.1 30.2 32.7                            G + F    0.5 + 0.5 18.9   17.4 17.3 23.5 20.5 19.5                                     0.5 + 1.0 10.6   10.4 10.7 10.7 10.8 10.6                                     1.0 + 0.5 20.2   25.5 21.3 15.7 23.6 21.3                                     1.0 + 1.0 10.1   8.5  10.3 11.8 14.2 11.0                            ______________________________________                                         rep. = repetition                                                        

Compared to the untreated control 1 kg./ha. of 2-chloroethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-esterdecreased the growth of sunflower by 1/6 and the dose of 2.0 kg./ha.decreased its height by approximately 1/3. As a result of similar dosesof 2-chloro-ethyl-phosphonic acid the height growth amounted only to 1/6of the value of the control.

2,2-Dimethyl-2,3-dihydro-7-hydroxy-benzofuran did not significantlyinfluence the growth.

When using 2-chloro-ethyl-phosphonic acid and2,2-dimethyl-(2,3-dihydro-7-hydroxy)-benzofuran in a mixture of variousactive ingredient ratios the depressant activity of2-chloro-ethyl-phosphonic acid decreased. It further shows that by usingan 1:1 mixture of the two compounds the depressant activity of2-chloro-ethyl-phosphonic acid somewhat decreased.

                  TABLE 4                                                         ______________________________________                                        Effect of pre-emergent treatment on the growth of tomato                                      Change in the % of the starting                                       Treatment                                                                             height                                                                  dose      I.     II.   III. IV.                                     Composition                                                                             kg./ha.   rep.   rep.  rep. rep.  .sup.--X                          ______________________________________                                        K                   28.4   31.3  27.5 26.1  28.3                              Compound  1.0       28.6   29.5  30.7 31.6  30.1                              2         2.0       35.2   33.1  30.8 32.6  32.9                                        4.0       26.2   24.5  26.3 25.2  25.6                                        8.0       20.8   17.6  18.9 17.1  18.6                              F         2.0       27.5   26.9  33.1 28.2  28.9                              G         2.0       33.1   32.6  29.8 32.9  32.1                              ______________________________________                                         rep.: repetition                                                         

When testing the activity of the compositions through the soil it can beobserved that when spraying 2-chloro-ethyl-phosphonic acid on the soilno plant growth regulating activity is exhibited. A rate of 2 kg./ha. of2,2-dimethyl-2,3-dihydro-7-hydroxy-benzofuran stimulated the growthsimilarly to 1 and 2 kg./ha. resp. of 2-chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester. Thegrowth of tomato at a rate of 4 kg./ha. is moderate whereas at a rate of8 kg./ha. the growth was reduced by 1/3.

In green house tests in culture dishes the plant growth regulatingactivity of 2-chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethylbenzofuran-7-yl)-ester wastested pre-emergence and post-emergence by using tomato, soybeans andsunflowers as test plants.

The height of tomato was increased by using 2-chloro-ethyl-phosphonicacid-O-methyl-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester, theextent of the growth was in inverse ratio to the dose. The activity ofthe active ingredient depends on the tested arts and on the developmentstage of the plants. The height of the soybeans and the sunflowers wasreduced by the doses used on tomato proportionally with the amount ofthe active ingredient used pro hectare.

2-Chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester asopposed to 2-chloro-ethyl-phosphonic acid when treated pre-emergence intomato can act as plant growth regulator by being absorbed from the soilthrough the route.

The biological tests were repeated under the disclosed test conditionson the mentioned plants. As active ingredient 2-chloro-ethyl-phosphonicacid-O-methyl-(4-methyl-coumarin-7-yl)-ester (Compound No. 7) and asreferential compounds 2-chloro-ethyl-phosphonic acid (F) and7-hydroxy-4-methyl-coumarin (M) were used next to the control (K).

                  TABLE 5                                                         ______________________________________                                        Effect of post-emergence treatment on the growth of tomato                            Treatment                                                                              Change in the % of the start-                                        dose     ing height                                                   Composition                                                                             kg./ha.    4. day    7. day                                                                              10. day                                  ______________________________________                                        K                    29        53    71                                       Compound  0.5        38        73    90                                       No. 7     1.0        44        81    95                                                 2.0        40        66    83                                       F         0.5        42        69    86                                                 1.0        41        68    76                                                 2.0        43        65    70                                       M         0.5        33        60    72                                                 1.0        35        64    78                                                 2.0        37        70    82                                       ______________________________________                                    

The results of Table 5 show that 2-chloro-ethyl-phosphonicacid-O-methyl-(4'-methyl-coumarin-7'-yl)-ester significantly increasedthe growth of the tomato related to the untreated control. The activitycan be characterized as a function of the dose by a curve of secondorder the peak of which is at the dose of 1 kg./ha. By furtherincreasing the dose the composition already shows mainly a growthinhibiting activity. It can be seen further that the growth stimulatingactivity is more intensive than that of 7-hydroxy-4-methyl-coumarin andat higher doses the growth inhibiting activity is lower than that of2-chloro-ethyl-phosphonic acid.

                  TABLE 6                                                         ______________________________________                                        Effect of post-emergent treatments on the growth of soybeans                         Treat-                                                                        ment                                                                          dose  Change in the % of starting height                               Composition                                                                            kg./ha. I.     II.  III. IV.  V.   Average                           ______________________________________                                        K                23.4   26.9 21.1 25.1 26.2 24.5                              Compound 0.5     18.2   22.4 26.0 22.4 23.6 22.5                              No. 7    1.0     19.3   21.1 22.6 20.8 21.2 21.0                                       2.0     15.4   13.2 15.7 16.0 15.1 15.1                              F        0.5     13.0   11.3 14.1 15.1 9.4  12.6                                       1.0     15.1   10.6 12.4 11.4 11.4 12.2                                       2.0     6.6    10.0 8.5  9.5  8.8  8.7                               M        0.5     30.7   31.0 31.5 33.2 35.4 32.4                                       1.0     24.2   30.1 30.2 24.1 29.8 27.7                                       2.0     21.9   19.0 20.0 20.2 18.7 20.0                              ______________________________________                                    

When using 2-chloro-ethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester in soybeans all thethree tested doses reduced the height of soybeans differently from theresults observed on tomato. The extent of the reduction of the heightwas lower than the values measured for 2-chloro-ethyl-phosphonic acidwith similar rates. 0.5 kg./ha. of 7-hydroxy-4-methyl-coumarinstimulated whereas 2 kg./ha. of the same coumpound inhibited the growth.

                  TABLE 7                                                         ______________________________________                                        Effect of post-emergent treatments on the growth of sunflower                         Treat-                                                                        ment     Change in the % of starting the                              Compo-  dose     height                                                       sition  kg./ha.  I.     II.  III. IV.. V.   Average                           ______________________________________                                        K                33.0   38.8 31.1 27.9 26.7 31.5                              Compound                                                                              1.0      22.1   20.8 23.0 24.1 23.7 22.7                              No. 7   2.0      19.3   17.6 20.1 18.9 21.1 19.4                              F       1.0      6.3    5.0  6.1  5.4  6.2  5.8                                       2.0      5.8    5.1  5.0  4.0  2.7  4.5                               M       1.0      31.3   34.6 29.8 30.5 32.4 31.7                              M       2.0      27.4   28.2 27.5 26.9 28.1 27.6                              M + F   0.5 + 0.5                                                                              20.3   19.8 21.0 19.5 20.4 20.2                                      1.0 + 0.5                                                                              9.9    10.4 9.2  9.5  10.0 9.8                                       0.5 + 1.0                                                                              21.4   25.0 22.0 21.3 24.2 22.8                                      1.0 + 1.0                                                                              9.5    9.1  10.6 10.2 11.4 10.2                              ______________________________________                                    

When compared with the untreated control 2-chloro-ethyl-phosphonicacid-O-methyl-O-(4-methyl-coumarin-7-yl)-ester reduced the growth ofsunflower at both of the tested doses. The plant growth was intensivelyinhibited by 2-chloro-ethyl-phosphonic acid whereas 1 kg./ha. of7-hydroxy-4-methyl-coumarin did not effect the growth of sunflower and 2kg./ha. of the same compound slightly inhibited its growth. A mixture of2-chloro-ethyl-phosphonic acid and 7-hydroxy-4-methyl-coumarin atvarious active ingredient's ratios it could be observed that thedepressant activity of 2-chloro-ethyl-phosphonic acid was moderated bythe 7-hydroxy-4-methyl-coumarin.

                  TABLE 8                                                         ______________________________________                                        Effect of pre-emergent treatment on the growth of tomato                             Treatment                                                                              Change in the % of                                                   dose     the starting height                                           Composition                                                                            kg./ha.    I.     II.  III. IV.  Average                             ______________________________________                                        K                   28.4   31.3 27.5 26.1 28.3                                Compound 1.0        32.1   33.6 30.8 31.5 32.0                                No. 7    2.0        35.8   36.1 33.4 34.1 34.9                                         4.0        27.2   25.1 25.8 24.7 25.2                                         8.0        17.4   19.2 17.6 17.0 17.8                                F        2.0        27.5   26.9 33.1 28.2 28.9                                M        2.0        30.1   34.6 30.8 32.9 32.1                                ______________________________________                                    

When evaluating the activity of the compositions through the soil itshows that 2-chloro-ethyl-phosphonic acid does not act as plant growthregulator through the roots.

2kg./ha. of 7-hydroxy-4-methyl-coumarin stimulated the growth similarlyto 1 and 2 kg./ha. of 2-chloro-ethyl-phosphonicacid-O-methyl-O-(4-methyl-coumarin-7-yl)-ester. By increasing the dosepro hectare to 4 and 8 kg./ha. the growth of tomato was alreadymoderated.

When spraying 2-chloro-methyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7-yl)-ester on the foliage theheight of tomato was increased. The growth of soybeans and sunflowers atthe tested doses was reduced by the active ingredient.

When treating tomato pre-emergence 2-chloro-ethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester was sprayed on the soiland the active ingredient penetrated through the root of the plants andacted as plant growth regulator which could be observed in the change ofthe height of tomato.

Under the given test conditions further biological tests were carriedout on the mentioned test plants. As active ingredient2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester and asreferential compounds 2-chloro-ethyl-phosphonic acids (F) and2,3-dihydro-2,2-dimethyl-7-hydroxy-benzofuran (N) were used next to thecontrol (K).

                  TABLE 9                                                         ______________________________________                                        Effect of post-emergent treatments on the growth of soybeans                         Treatment Change in the % of the starting                              Compo- dose      height                                                       sition kg./ha.   I.     II.  III. IV.  V.   Average                           ______________________________________                                        K                23.4   26.9 21.1 25.1 26.2 24.5                              Comp.  0.5       14.9   15.1 13.6 14.8 14.1 14.5                              No. 1  1.0       13.7   14.0 14.6 14.1 13.8 14.0                                     2.0       13.1   13.5 12.9 13.6 13.0 13.2                              F      0.5       13.0   11.3 14.1 15.1 9.4  12.6                                     1.0       15.1   10.6 12.4 11.4 11.4 12.2                                     2.0       6.6    10.0 8.5  9.5  8.8  8.7                               N      0.5       33.8   28.2 32.6 37.6 33.3 33.1                                     1.0       22.6   30.4 35.8 22.1 33.8 28.9                                     2.0       23.8   18.4 20.5 20.6 19.5 20.6                              ______________________________________                                    

After the evaluation of the biological activity of2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester it shows thatthe soybeans' growth is influenced by the compound. In the tested periodthe height of the untreated plants increased on an average by 24.5%whereas the height of the plants treated by various doses of2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester by 13%.

                  TABLE 10                                                        ______________________________________                                        Effect of post-emergent treatment on the growth of sunflower                         Treatment Change in the % of the starting                              Compo- dose      height                                                       sition kg./ha.   I.     II.  III. IV.  V.   Average                           ______________________________________                                        K                33.0   38.8 31.1 27.9 26.7 31.5                              Comp.  1.0       8.7    10.3 9.4  9.7  10.0 9.6                               No. 1  2.0       7.5    6.6  8.0  6.4  7.0  7.1                               F      1.0       6.3    5.0  6.1  5.4  6.2  5.8                                      2.0       5.8    5.1  5.0  4.0  2.7  4.5                               N      1.0       27.8   25.0 38.9 33.3 26.5 30.3                                     2.0       32.9   35.0 35.3 30.1 30.2 32.7                              N + F  0.5 + 0.5 18.9   17.4 17.3 23.5 20.5 19.5                                     0.5 + 1.0 10.6   10.4 10.7 10.7 10.8 10.6                                     1.0 + 0.5 20.2   25.5 21.3 15.7 23.6 21.3                                     1.0 + 1.0 10.1   8.5  10.3 11.8 14.2 11.0                              ______________________________________                                    

The growth of sunflower was significantly reduced by2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester when comparingwith the untreated control. During the test period the height of theuntreated control was increased by 31.5% related to the starting valuewhereas the height of the plants treated with the compound according tothe invention was increased only by 9.6-7.1%. The compounds were used incombinations of various ratios thus 2-chloro-ethyl phosphonic acid and2,3-dihydro-2,2-dimethyl-7-hydroxy-benzofuran were used at rates of 1kg./ha.+0.5 kg./ha. and 1 kg./ha.+1 kg./ha. and none of thesecombinations achieved the plant growth regulating activity of thecompound according to the invention.

                  TABLE 11                                                        ______________________________________                                        Effect of pre-emergent treatments on the growth of tomato                            Treatment                                                                              Change in the % of the starting                                      dose     height                                                        Composition                                                                            kg./ha.    I.     II.  III. IV.  Average                             ______________________________________                                        K                   28.4   31.3 27.5 26.1 28.3                                Compound 1.0        38.6   40.2 37.9 38.3 38.8                                No. 1    2.0        43.2   41.8 42.0 39.6 41.2                                         4.0        41.7   44.6 43.9 42.7 43.2                                         8.0        21.4   19.6 24.3 20.5 21.5                                F        2.0        27.5   26.9 33.1 28.2 28.9                                N        2.0        33.1   32.6 29.8 32.9 32.1                                ______________________________________                                    

2-Chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester was usedpre-emergence and when evaluating the biological activity of thecompound an intensive plant growth stimulating activity can be seen ontomato showing the composition was absorbed by the plant from the soil.The growth of the untreated control was in the tested period 28.3%related to the starting height. The growth of the plants treated with1-4 kg./ha. of 2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester was 38.8-43.2%.By increasing the dose of the composition to 8 kg./ha. the growthstimulation turned over to growth inhibition. The test results can besummarized as follows:

By spraying 2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester on soybeans andsunflower a significant growth inhibition could be observed related tothe untreated control. On the basis of the growth inhibition it can besaid that 2-chloro-ethyl-phosphonicacid-(2,3-dimethyl-benzofuran-7-yl)-ester regulates the plant growthwhen used post-emergence. In case of a treatment pre-emergence the plantgrowth regulating activity of 2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester can be similarlyobserved as proved by the tests carried out e.g. on tomatoe.

The post-emergent activity of the compositions according to theinvention was also tested in free land tests on soybeans, maize, winterwheat and red pepper. The results of the test are shown in the followingtables.

SOYBEANS Test conditions

Type of soil: field chernozem

Green-crop: sugar beet

Fertilization:

50 kg./ha. N(ammonium-nitrate)

100 kg./ha. P₂ O₅ (superphosphate of 18%)

120 kg./ha. K₂ O (potassium chloride of 50%)

Weed killing: 910 g./ha.2,6-dinitro-N,N-dipropyl-4-trifluoro-methyl-aniline+900 g./ha.N-(4-bromo-3-chloro-phenyl)-N'-methoxy-N'-methyl-urea

Art: ISz-15

Stock-number: 350,000 stock/ha.

Parcel size: 2×10 m.

Repetitions: 6

Spray liquid: 200 l./ha.

Treatments:

(1) untreated control

(2) 2-chloroethyl-phosphonic acid: 250 g./ha.

(3) 2-chloroethyl-phosphonic acid: 500 g./ha.

(4) 2-chloroethyl-phosphonic acid: 1000 g./ha.

(5) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 250 g./ha.

(6) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 500 g./ha.

(7) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 1000 g./ha.

(8) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)ester: 250 g./ha.

(9) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 500 g./ha.

(10) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 1000 g./ha.

The spraying was carried out at the beginning of the budding of thesoybeans. The spray liquid concentration changed in the range of 1.13g./l. to 4.54 g./l. related to the active ingredient.

Compositions disclosed in Examples 3 and 8 were used.

                  TABLE 12                                                        ______________________________________                                        Effect of post-emergent treatment on soybeans' crop                                                          Change in the                                  Number of Dose      Crop average                                                                             % of the                                       treament  g./ha.    t./ha.     control                                        ______________________________________                                         1.       --        2.60       100                                            2         250       2.68       103                                            3         500       2.32        89                                            4         1000      2.05        79                                            5         250       3.00       115                                            6         500       2.90       111                                            7         1000      2.74       105                                            8         250       2.98       115                                            9         500       3.00       115                                            10        1000      2.82       108                                            ______________________________________                                    

The results show that the compounds according to the invention increasedthe crop as opposed to 2-chloro-ethyl-phosphonic acid.

A 15% crop increase was measured at a rate of 250 g./ha.2-chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester and2-chloro-ethyl-phosphonicacid-O-methyl-O-(4-methyl-coumarin-7-yl)-ester. By increasing the doseto 1000 g./ha. the crop increase amounted only to 5-8%, the crop,however, was reduced to 21% by the same dose of2-chloro-ethyl-phosphonic acid.

WINTER WHEAT Test conditions

Type of soil: field chernozem

Green-crop: green peas

Fertilization:

200 kg./ha. N(ammonium-nitrate)

120 kg./ha. P₂ O₅ (superphosphate of 18%)

140 kg./ha. K₂ O (potassium chloride of 50%)

Weed killing: 1000 g./ha. ammonium salt of 2,4-dichloro-phenoxy-aceticacid

Art: Mv-80

Stock number: 5.5 million stock/ha.

Parcel size: 2×10 m.

Repetitions: 6

Spray liquid: 220 l./ha.

Treatments:

(1) untreated control

(2) 2-chloroethyl-phosphonic acid: 500 g./ha.

(3) 2-chloroethyl-phosphonic acid: 1000 g./ha.

(4) 2-chloroethyl-phosphonic acid: 2000 g./ha.

(5)2-chloroethyl-phosphonicaacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester:500 g./ha.

(6) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 1000 g./ha.

(7) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 2000 g./ha.

(8) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 500 g./ha.

(9) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)ester: 1000 g./ha.

(10) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 2000 g./ha.

(11) 2-chloroethyl-phosphonic acid: 50 g./ha.

(12) 2-chloroethyl-phosphonic acid: 100 g./ha.

(13) 2-chloroethyl-phosphonic acid: 200 g./ha.

(14) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 50 g./ha.

(15) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 100 g./ha.

(16) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 200 g./ha.

(17) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 50 g./ha.

(18) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 100 g./ha.

(19) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 200 g./ha.

Treatments number 2 to 10 were performed when growing into thick andtreatments 11-19 were performed during earing. The spray liquidconcentration changed in the range of 0.22 g./l. to 9.1 g./l. related tothe active ingredient. Compositions disclosed in Examples 3 and 8 wereused.

                  TABLE 13                                                        ______________________________________                                        Effect of post-emergent treatments on the crop of winter wheat                                               Change in the                                  Number of Dose      Crop average                                                                             % of the                                       treatment g./ha.    t./ha.     control                                        ______________________________________                                        1         --        7.75       100                                            2         500       7.82       101                                            3         1000      7.53        97                                            4         2000      6.79        87                                            5         500       8.66       112                                            6         1000      8.51       110                                            7         2000      8.46       109                                            8         500       8.80       114                                            9         1000      8.97       116                                            10        2000      8.88       115                                            11         50       7.74       100                                            12        100       7.88       102                                            13        200       7.44        96                                            14         50       7.91       102                                            15        100       8.38       108                                            16        200       8.17       105                                            17         50       7.86       101                                            18        100       8.30       107                                            19        200       8.53       110                                            ______________________________________                                    

The data of the results performed on winter wheat show that whenspraying the compositions according to the invention when growing intothick the crop was increased at the tested ratios by more than 10%. Thecrop was not influenced by 2-chloro-ethyl-phosphonic acid or it wasreduced by higher rates of the same compound. When using thecompositions according to the invention during the earing and 5-10% cropincrease was measured at rates of 100-200 g./ha. At the same time2-chloro-ethyl-phosphonic acid was applied and substantially no changein the crop could be observed.

MAIZE Test conditions

Soil type: field chernozem

Green-crop: winter wheat

Fertilization:

250 kg./ha. N(ammonium-nitrate)

140 kg./ha. P₂ O₅ (18% superphosphate)

180 kg./ha. K₂ O (50% potassium chloride)

Weed killing: 2000 g./ha.N-(ethoxy-methyl)-2-ethyl-6-methyl-chloro-acetanilide+1000 g./ha.N-(4-bromo-3-chloro-phenyl)-N'-methoxy-N'-methyl-urea

Art: Pioneer 3709

Stock number: 82,000 stock/ha.

Parcel size: 2.1×10 m.

Repetition: 6

Spray liquid: 220 l./ha.

Treatments:

(1) Untreated control

(2) 2-chloroethyl-phosphonic acid: 500 g./ha.

(3) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 250 g./ha.

(4) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 500 g./ha.

(5) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 1000 g./ha.

(6) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 250 g./ha.

(7) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 500 g./ha.

(8) 2-chloroethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester: 1000 g./ha.

The treatments were performed at the stage of 6-8 leaves, the sprayliquid concentration was in the range of 1.13 g./l. to 4.54 g./l.related to the active ingredient. Compositions disclosed in Examples 3and 8 were used.

                  TABLE 14                                                        ______________________________________                                        Effect of post-emergent treatment on the crop of maize                        Number of                                                                              Dose     Crop average                                                                              Change in the % of                              treatment                                                                              g./ha.   t./ha.      the control                                     ______________________________________                                        1        --       7.12        100                                             2        500      5.68         80                                             3        250      8.30        117                                             4        500      7.94        112                                             5        1000     6.97         98                                             6        250      8.56        120                                             7        500      8.03        113                                             8        1000     7.21        101                                             ______________________________________                                    

2-Chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester and2-chloro-ethyl-phosphonicacid-O-methyl-O-(4'-methyl-coumarin-7'-yl)-ester were tested on maizeand the crop was increased by 17-20% at a rate of 250 g./ha. Byincreasing the dose the crop increase was reduced and at a rate of 1000g./ha. there was no more difference related to the untreated control. Asopposed to the compounds according to the invention 500 g./ha. of2-chloro-ethyl-phosphonic acid reduced the crop by 20%.

RED PEPPER Test conditions

Soil type: field chernozem

Green crop: onion

Fertilization: 40 t./ha. organic fertilizer

Weed killing: 910 g./ha.2,6-dinitro-N,N-dipropyl-4-trifluoro-methyl-aniline+manual hoeing

Art: Szegedi spicy F 03 red pepper

Stock number: 365,000 stock/ha.

Parcel size: 2×10 m.

Repetition: 6

Spray liquid: 220 l./ha.

Treatments:

(1) Untreated control

(2) 2-chloroethyl-phosphonic acid: 1000 g./ha.

(3) 2-chloroethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester: 1000 g./ha.

(4) 2-chloroethyl-phosphonicacid-O-methyl-(4'-methyl-coumarin-7'-yl)-ester: 1000 g./ha.

The spraying was performed at the beginning of the colourization of thepepper. The spray liquid concentration amounted to 4.54 g./l, related tothe active ingredient. Compositions disclosed in Examples 3 and 8 wereused.

                                      TABLE 15                                    __________________________________________________________________________    Effect of post-emergent treatment on the crop and qualitative parameters      of red pepper                                                                 Composition,  Ratio of  The colour distribution of ripe                       number of                                                                            Crop   green     peppers %                                             treatment                                                                            t./h.                                                                             %  peppers %                                                                           Dye %                                                                             completely ripe                                                                       semi-ripe                                                                          worthless                                __________________________________________________________________________    1      3.15                                                                              100                                                                              28    8.84                                                                              42.5    22.6 43.8                                     2      2.85                                                                               90                                                                              25    10.07                                                                             51.2    28.4 20.4                                     3      3.55                                                                              113                                                                              20    9.98                                                                              70.1    11.4 18.5                                     4      3.60                                                                              114                                                                              20    9.65                                                                              72.3    9.7  18.0                                     __________________________________________________________________________

According to the test results carried out on red pepper the compoundsaccording to the invention increased the crop by 13-14% whereas thetreatment with 2-chloro-ethyl-phosphonic acid reduced the crop. Theratio of completely green peppers was also less. The amount of colouringsubstances was increased related to the untreated control but did notachieve the value measured for 2-chloro-ethyl-phosphonic acid.

When testing the coloured peppers it shows that the ratio of thecompletely ripe peppers giving the best quality achieved 70% on parcelstreated with the compounds according to the invention. The ratio ofsemi-ripe and brown worthless peppers was significantly lower than incase of the untreated control or on parcels treated with2-chloro-ethyl-phosphonic acid.

We claim:
 1. 2-Chloro-ethyl-phosphonic acid esters of the generalFormula (I) ##STR12## wherein R stands for hydrogen, C₁₋₈ straight orbranched chained alkyl, C₁₋₄ haloalkyl, C₁₋₄ alkoxy-C₁₋₂ alkyl,R¹ standsfor 2,3-dihydro-2,2-dimethyl-benzofuran-7-yl, 4-methyl-coumarin-7-yl,2,2,4-trimethyl-(2H)-chromen-5-yl or 2,2,4-trimethyl-(2H)-chromen-7-yland Me stands for a monovalent cation and represents the salt of theacid.
 2. 2-Chloro-ethyl-phosphonicacid-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester. 3.2-Chloroethyl-phosphonic acid-O-(4'-methyl-coumarin-7'-yl)-ester. 4.2-Chloro-ethyl-phosphonicacid-O-methyl-O-(2,3-dihydro-2,2-dimethyl-benzofuran-7-yl)-ester. 5.Plant growth regulating compositions containing as active ingredient2-chloro-ethyl-phosphonic acid derivative of the general formula I ofclaim 1 whereinR stands for hydrogen, C₁₋₈ straight or branched chainedalkyl, C₁₋₄ haloalkyl, C₁₋₄ alkoxy-C₁₋₂ alkyl, R¹ stands for2,3-dihydro-2,2-dimethyl-benzofuran-7-yl, 4-methyl-coumarin-7-yl,2,2,4-trimethyl-(2H)-chromen-5-yl or 2,2,4-trimethyl-(2H)-chromen-7-yland Me stands for a monovalent cationtogether with solid and/or liquidcarriers and optionally surfactants.
 6. Method of treatment of plantspre or post emergence comprising applying an effective amount of acompound of the general formula (I) as claimed in claim 1 to the plantsor its surroundings.